Tissue Optical Clearing Devices: Effects of Water Content on the Hyperelastic Mechanical Properties of Ex Vivo Porcine Skin

Skin is a highly anisotropic and heterogeneous material composed of water, proteins, and various cells arranged in several different layers. Because of this complex structure, there is a large mismatch in index of refraction between the tissue constituents, creating a highly scattering medium for near-infrared and visible light. “Tissue optical clearing” methods can improve light transmission through tissues, potentially improving optical imaging techniques and photoirradiative treatments [1]. Dehydration has been suggested as a possible mechanism of optical clearing [2], and previous work has demonstrated mechanical loading as a method of creating reversible localized water displacement in skin using novel tissue optical clearing devices (TOCDs) [3–4]. These TOCDs were hypothesized to increase light transmission by displacing water locally in the tissue, causing local dehydration. A model of the mechanical behavior of skin will enable improvement of current TOCDs that utilize local mechanical compression.